B-Unit

iTrader: (21)

Allright guys, im going to begin piecing my system together, so this is going to be my worklog/helplog/advice thread. Im going to start it out with general questions on simply what audio parts to get. But with finals ending next week, I am going to be making a trip down to Lowes to get my MDF and begine the fiberglass box construction. So I will be posting pics and doing a sort of HOW-TO with the fiberglassing and amp rack construction and all that fun stuff.

So here we go. The first step is beginning! The parts...

Now im famiiar with good audio parts. Ive looked into Phoenix Gold, Elemental Designs, Kicker, Infinity, and I always find myself comming back to the freaking JLs. So without a doubt im going to be using JL equipment. Now i know allot of people like to mix and match equipment, for the sake of keeping it clean (matching my car) and professional, im going to be sticking with all JL stuff, amps, subs, maybe door speakers (I havent decided yet).

The Sub decision...

Allright, my first question comes with subs, im going to be doing this project one step at a time, and Im deciding to start with the box design and the subs. Im going to be getting the w7 series subs, but I am having a very difficult time deciding between 2- 10"w7s, 1- 12"w7, or 1- 10"w7. Right now, im leaning towards 1-12 becuase i feel like 2- 10s will destroy me, especially with the w7s, not to mention buying two 10s will be the most expensive, by about 250 buks. So im leaning towards 1- 12, how do you guys think that will perform as opposed to the other options Ive listed? I know that 10s are usually tighther in regards to keepin with the beats, but these w7s are soo top notch, i think a 12 keeping up with fast paced bass beats will not be an issue.

That being said, next comes the sub box. I am a total newb when it comes to calculating airspace. Since its in cubic inches/feet, i would assume i calculate the box space by the (base area of the box) x (the height). So how do i decide how much space i need, the subs are rated for a certain amount of airspace for each sub. Do i need to be right on with the airspace, or is a little under/over allright. Is it better to be under the recomended airspace, or worse to be over the recommended (so should i shoot for a lil extra as opposed to a lil less??)

Cutting the box will not be a problem, i have experience with dremels and jigsaws so the cutting is not what I am concerned about, its more of the design stuff.

Thanx and help would be greatly appreciated as everyone on the site benefits and enjoys participating and viewing worklogs!

-Bryan-

stu46

Go with 1 10w7. The space you save will overcome the sound you gain.

It's ok if you deviate a little over/under the space requirements.

Badfish25

iTrader: (3)

Why JL, you could probably save yourself some $and go all ED, I just posted up a thread with my finished install, and DAMN everything sounds good!
JL has good stuff, so if you stay with them, just go for a single 10" there are alot of nice prefabed boxesfor a 10 in the Z.

B-Unit

iTrader: (21)

OK, sweet, yeah 1- 10" sounds pretty sweet from a space stand point. Im still going with the same type of box (the box in the Dactive Tuning Z). I hope this 1- 10 will still hit, im sure it will. Badfish, do you have a single 10" as well?

stu46

There was someone here that had 2 10w7 and removed one because it was too loud. Are you going ported or sealed?

B-Unit

iTrader: (21)

Sealed and glassed. Like the Active Tuning system, identical except with a 10" woofer.

Heres a pic..





On a side note, i purchased a 10"w7 yesterday, so im taking your guys' advice and goin with 1- 10w7.

Now its time to build the box!

stu46

you know, I just noticed your ND sig....lol awesome! my gf got me the liger and sledgehammer tshirt from hot topic for my bday. my friend got the vote for pedro and kip's "I'm training to be a cage fighter" shirt.

B-Unit

iTrader: (21)

Haha, yeah, i like that movie to say the least, it cracks me up.

Badfish25

iTrader: (3)

No I actually have a single 12". I had the sub from my previous car and didn't feel like selling it and buying the 10" version.

B-Unit

iTrader: (21)

OK everyone, time to revive this thread! I went out yesterday and bought a bunch of 3/4" MDF, so now its time to start building the box. I have some questions concerning airspace with concerns of mounting depth etc.

OK, so i have the JL 10w7 sub that im putting in this box and it has a mounting depth of 8". How should this affect the dimensions of a box with a woofer that say needs 6" of mounting depth? Does this mean, that the box should be 8" from the back of my magnet, im kinda confused as to what this mounting depth requires from me in concerns of the dimensions of my box.

Thanx.

B-Unit

iTrader: (21)

If anyone could give me a hand figuring out the dimensions of this box under the strut for my 10, i would greatly appreciate it.

-B-

Paul350Z

iTrader: (1)

http://www.jlaudio.com/subwoofers/pdfs/12W7_MAN.pdf

Lists the following measurements for the W7 12"

Qts 0.482
Vas 2.33
Fs 27.2

I'm going to use a couple of Qtc figures to get box sizes for you.

A box with a Qtc of 1.1 will have abit of a bass boost without sounding too boomy and will require a size of 0.554 cubic feet (pretty darn small) and have a F3 (-3 dB down point) of 47 Hz.

A box with a Qtc of .707 will have the most natural sounding and accurate sound with the lowest possible F3 number. You'll need 2.0 cubic feet of space and get an F3 frequency of 40 Hz.

Here's the Java calculator to play with for yourself:
http://www.carstereo.com/help/Articles.cfm?id=26

Here's the link that explains what Qtc is:
http://www.carstereo.com/help/Articles.cfm?id=29

Personally I like a bit of bass boost but not a whole lot - a Qtc of 0.9 is what I'm looking for.

Paul

Paul350Z

iTrader: (1)

PS: Here's a subwoofer box volume calculator for your use.

http://www.carstereo.com/help/Articles.cfm?id=5

bknezevic

Here's my set up with a 12w7, JL 1000/1, 300/4 and XR 650-csi and XR650-cxis





For all pictures and details the thread is here .... https://my350z.com/forum/showthread....1553781&conly=

B-Unit

iTrader: (21)

Thanx Paul, i was looking at JLs site, and they recomend one thats kind of in the middle, i was looking for the 10w7, heres what they say.

For a sealed Enclosure

Net Volume: 1.25 Cu Ft.
FC: 44.7 Hz F3: 40.7 Hz QTc: 0.785

I guess they are giving me the dimensions that will allow it to sound the most natural.

So lemme see if i understand this.

So if i want to change the F3,and the Qtc to obtain a bass boost, all i need to do is make the box smaller. So Assuming that i want a qtc of 1.1 which means a frequency of around 47.43 Hz, im going to need a box that has a VB of 0.4 Cu Ft.

This is considerable smaller box than what JL recommends on their spec sheet. So heres my question, what happens if i build a box where the airspace is somewhere between 0.4 Cu Ft. and 1.28 Cu. Ft. ?? Will i just be getting less of a bass boost as i get closer to 1.28? And once i hit 1.28 does this mean my sub will still put out a crap load of bass with say rap, etc. ?

Thanx i think im beginning to understand this a little better.

B-Unit

iTrader: (21)

Heres another question..

When i put in the cu Ft on that box calculator, lets say i want 1.0 cu ft of air space, so i put that in, and it gives me this

Depth= 7.2 in.
Height= 19.44 in.
Width= 12 in.

Supposing if i want to put this under my strut bar, i dont think that a 19" height will work to well, so if i interchange the dimensions, yet keep them the same as those numbers, just make the depth the width or something, will this work? or is it giving me the space it needs to be to work the best? i would think it wouldnt matter cuz its airspace either way you look at it, but what about the mounting depth of the driver? does this affect it?


Thanx

Paul350Z

iTrader: (1)

Qtc's above 1.2 sound boomy (cheap) and colored. If you're looking for the boom-boom over music then by all means sacrafice the lower more accurate frequency response for the gain from a smaller box. It's your music to destroy

The calculator gives you "golden" size ratios built on the 3-4-5 (IIRC) ratio which will elimate standing waves inside the box.

Here's another one which deals with a wedge shape like the under strut boxes. I found it after having to remember the area of triangles formula. I got 0.75 giving up a tad for the internal bracing BTW.

http://www.audiogrid.com/audio/

B-Unit

iTrader: (21)

So personally Paul, how much airspace do YOU think would give me the best performance but allow me to crank up the serious bass when needed. Prolly around like .80 cu Ft ??

Also, the fiberglassing of the front of the box is going to create some extra airspace, so with the box, i should probably make it a little smaller than my desired airspace becauase of the added space with the glassing in the front.

-B-

Paul350Z

iTrader: (1)

I ran the 10W7 in my little .75 cu.ft. box and its not a bad match at all with a Qtc of .95 and an F3 of 46 Hz.

You're using only one driver correct?

For a more boom-boom sound without going too far using a Qtc of 1.2 you need to pack that speaker into a tiny box of just .186 cu. feet!

A Qtc of 1 will require a box of 0.314 cu.ft.

A perfect .707 Qtc will need 1.436 feet

This chart takes a subwoofer with a SPL of 90 can plots it's response with various Qtc's. Note the big bumb with the 1.5 Qtc and the nice smooth roll off of the .707.



Adding a second subwoofer will drastically alter the sound of the box so let me know if you're going to scratch up more dough.

B-Unit

iTrader: (21)

Nah, this may not mean too much, but i dont really want the extra weight of another one of these w7s, plus the extra money. I think 1 driver should be enough to hit hard like a mother, but i enjoy listening to Jazz, classical, rock, etc. I just want clean, but the ability to really bump if im listeing to some G-Unit or whatever.